Drill bit having regenerative nanofilms

ABSTRACT

A system of repairing and protecting a surface of a drill bit includes forming a drill bit body that includes a magnetized material or is otherwise magnetizable. The drill bit includes at least one cutting element and is operable to generate a magnetic field. A drilling fluid that includes magnetizable, regenerative particles is circulated through a drill string and wellbore in which the drill bit is deployed. The magnetic field attracts the regenerative particles to the surface of the drill bit body to occupy cracks and chips formed in the surface of the drill bit body, and to form a protective layer of the regenerative particles over the surface of the drill bit body.

1. TECHNICAL FIELD

The present disclosure relates to drill bits, drill bit materials, and related methods of use.

2. DESCRIPTION OF RELATED ART

Wells are drilled to access and produce oil, gas, minerals, and other naturally-occurring deposits from subterranean geological formations. The drilling of a well typically is accomplished with a drill bit that is rotated to advance the wellbore by removing topsoil, sand, clay, limestone, calcites, dolomites, or other materials from a formation. Pieces of such materials removed from the formation by the drill bit are generally referred to as “cuttings” or “drill cuttings.”

A drill bit is typically classified as either a fixed cutter drill bit or a rotary cone drill bit, which may also be referred to as a roller cone drill bit. Generally, a rotary cone drill bit includes a drill bit assembly having multiple rotating cones (i.e., “roller cones”) with cutting elements. The roller cones rotate relative to the drill bit assembly as the drill bit is rotated downhole. In contrast, a fixed cutter drill bit includes a drill bit body having cutting elements at fixed locations on the exterior of the drill bit body. The cutting elements remain at their fixed locations relative to the bit body as the drill bit is rotated downhole.

During drilling, the drill bit experiences some of the most intense strains and pressures of any component in the drill string. Some of the focus in bit design is to strengthen and increase the durability of drill bits. In some cases, material selection drives the durability of the drill bit, and steel bits and tungsten carbide bits have become popular because of their durability.

Fixed cutter and roller cone bit bodies are often formed of matrix materials, and each may be referred to, accordingly, as a matrix bit body. The materials used to form a matrix bit body may include a powder, which is typically a hard and durable material, and a binder material that holds the powder together to form the bit. Since the resulting matrix in many cases does not chemically bond the powder component and the binder together, the matrix drill bit may be susceptible to fracturing or other types of damage if it experiences sufficient chipping or other types of wear.

During drilling operations, the drill bit itself is perhaps under more stress than any other part of a drill string. In addition, damage to the drill bit may cause damage to other parts of the drill string, including the collar that couples the drill bit to the drill string and corresponding drive system. Small chips and cracks resulting from wear on the drill bit are a common source of such damage. The small chips in the structure of the drill bit may lead to bigger gaps forming, which may eventually lead to the complete destruction of the drill bit.

When the cost of down time for the well and drill string is considered, the cost of repairing a drill bit having minor damage may be significant.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present disclosure are described in detail below with reference to the attached drawing figures, which are incorporated by reference herein and wherein:

FIG. 1 illustrates a perspective view of one embodiment of a roller cone drill bit;

FIG. 2 illustrates an elevation view of the roller cone bit of FIG. 1 deployed in a drilling environment;

FIG. 3 illustrates a cross-section of one embodiment of a roller cone and spindle of a drill bit, as indicated by the section line A-A′ of FIG. 1, wherein the roller cone includes magnetic material and surrounding nanoparticles;

FIG. 4 illustrates a cross-section view of the roller cone of FIG. 3 in which the roller cone is regenerating a portion of its surface;

FIG. 5 illustrates a cross-section of a portion of a fixed cutter drill bit that includes magnetic material and surrounding nanoparticles;

FIG. 6 illustrates a cross-section view of the portion of the fixed cutter drill bit of FIG. 5 in which a portion of the surface of the drill bit is regenerating;

FIG. 7 is a schematic, cross-section view of a portion of a drill string that includes a drill bit that is magnetically coupled to an electromagnet; and

FIG. 8 is a block diagram of a drilling system that includes a drill bit that is magnetically coupled to an electromagnet.

The illustrated figures are only exemplary and are not intended to assert or imply any limitation with regard to the environment, architecture, design, or process in which different embodiments may be implemented.

DETAILED DESCRIPTION

In the following detailed description of the illustrative embodiments, reference is made to the accompanying drawings that form a part hereof. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosed systems, devices, and methods. It is understood that other embodiments may be utilized and that logical structural, mechanical, electrical, and chemical changes may be made without departing from the spirit or scope of the disclosure. To avoid detail not necessary to enable those skilled in the art to practice the embodiments described herein, the description may omit certain information known to those skilled in the art. The following detailed description, therefore, is not to be taken in a limiting sense; and the scope of the illustrative embodiments is defined only by the appended claims.

The embodiments described herein relate to drill bits that use magnetic forces to attract and magnetically join regenerative nanoparticles to improve the strength and durability of a drill bit by regenerating damaged surfaces of the drill bit's body and growing a protective nanofilm that protects the surface of the drill bit body. Regenerating materials, such as superparamagnetic iron oxide nanoparticles, are introduced into the drilling fluid and are magnetically attracted by magnetic particles in the bit body. The magnetic attraction between the regenerating materials and magnetic particles results in the regenerating materials being attracted to and attaching to surface of the drill bit body to fill small chips and other surface damage to the drill bit body, and may thereby “regenerate” the surface of the drill bit body. While the iron oxide particles described herein are generally contemplated as being superparamagnetic and sized on the nanoscale, it is noted that such particles may, in other embodiments, be paramagnetic and be sized on the microscale.

According to an illustrative embodiment, a wellbore formation system includes a drill bit having at least one cutting element and a drill bit body comprising a magnetized material that generates a magnetic field extending to and beyond an exterior surface of the drill bit body. The system further includes a drilling fluid that is populated with magnetizable, regenerative particles and a fluid flow path that guides the drilling fluid through a drill string and over a surface of the drill bit. The regenerative particles may be superparamagnetic nanoparticles, such as iron oxide. The drill bit body may be a matrix drill bit body that is formed from a particulate phase and a binder material. The particulate phase includes magnetic particles, such as ferromagnetic particles or particles of a rare earth magnet. In an embodiment in which the magnetic particles are ferromagnetic particles, the drill bit may include or be coupled to electromagnet that magnetizes the ferromagnetic particles. In another embodiment, the magnetic particles are particles of rare earth magnet, such as AlNiCo, neodymium, and samarium-cobalt, as described in more detail below. The drilling fluid may be a water-based drilling fluid or an oil-based drilling fluid. In an embodiment in which the drilling fluid is a water-based drilling fluid, the regenerative particles are functionalized for dissolution or suspension in water. In an embodiment in which the drilling fluid is an oil-based drilling fluid, the regenerative particles are functionalized for dissolution or suspension in oil.

Unless otherwise specified, any use of any form of the terms “connect,” “engage,” “couple,” “attach,” or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion and, thus, should be interpreted to mean “including, but not limited to.” Unless otherwise indicated, as used throughout this document, “or” does not require mutual exclusivity.

In an illustrative embodiment, the regenerative particles are nanoparticles having superparamagnetic properties. As referenced herein, superparamagneticism is a type of magnetism exhibited by ferromagnetic or ferrimagnetic particles composed of a single magnetic domain that become magnetized in the presence of a magnetic field. Such particles may be nanoparticles having dimensions of, for example, between 3 nanometers and 50 nanometers (nm), or any other suitable size. The nanoparticles may be iron oxide or other suitable types of materials. The two main forms of iron oxide are magnetite (Fe3O4) and its oxidized form maghemite (γ-Fe2O3). Iron oxide nanoparticles in the size range of 1 nm to 100 nm may exhibit superparamagneticism. When such nanoparticles are magnetized, the magnetization is considered a single magnetic moment that is the sum of all of the individual magnetic moments carried by the atoms of the nanoparticle. The nanoparticles are small, and may easily migrate through a drill string to a drill bit when deployed into a drilling fluid.

In some embodiments, the regenerative material is functionalized or processed to effectively dissolve or form a suspension in the drilling fluid. For example, a regenerative material such as superparamagnetic iron oxide may be functionalized with a polar or ionic compound to make it easily dissolvable in water or other polar solvents that serve as drilling fluid. In embodiments in which the drilling fluid is oil based, the regenerative materials may be functionalized or processed with non-polar molecules to facilitate dissolution or suspension in oil.

In an embodiment, the regenerating drill bit is a matrix drill bit that includes a magnetic material. In general, a matrix drill bit body is understood to be a drill bit body formed by placing a rigid powder or particulate phase material, typically in powder form, in a mold with a binder material, and heating the materials to cause the binder particles to grow together and bind the particulate phase material in the structure of the drill bit body. A typical particulate phase material for use on a drill bit body is tungsten carbide, and typical binder materials include copper and cobalt. The magnetic material included in the matrix drill bit may be in the form of particles of rare earth magnets that are added to the powder component or particulate phase of the matrix drill bit body. Alternatively, magnetic particles may be formed as the matrix drill bit is constructed by heating the matrix drill bit to the Curie temperature for the material used while applying a magnetic field. Other types of drill bits may also be used in which magnetic particles are incorporated in the drill bit body.

Referring now to the figures, FIG. 1 shows a perspective view of a roller cone drill bit, which is a common type of drill bit used in wellbore drilling. The roller cone drill bit 100, however, is merely an example of a commonly used type of drill bit, and the techniques described herein may be used in a variety of drill bits. Other suitable types of drill bits include fixed cutter drill bits, which are further described below. In an embodiment of a roller cone drill bit 100, rotating cones 102 have teeth 104 on their outer surface that function as cutting elements, and each rotating cone 102 is mounted on an arm 106 of the drill bit 100. The roller cone drill bit 100 may include a magnetic material embedded within the bit bodies of the roller cones 102.

FIG. 2 shows an elevation view, in partial cross-section, of a drilling rig that includes the roller cone drill bit 100 of FIG. 1. As illustrated in FIG. 2, a drill rig 208 uses sections of pipe 210 to transfer rotational force to a drill bit 200. A pump 212 is coupled to the pipe 210 and a drilling fluid source to circulate drilling fluid 214 (illustrated as flow arrows A) to the bottom of the wellbore through the sections of pipe 210 and through the drill bit 200 during drilling. As the drill bit 200 rotates, the applied weight-on bit (“WOB”) forces the downward pointing teeth of the rotating cones into the formation being drilled. The points of the teeth apply a compressive stress that exceeds the yield stress of the formation and induces fracturing in the formation. This fracturing produces cuttings that are removed from the formation to form the wellbore. The cuttings, however, may contact and induce frictional forces on the body of the drill bit, and may thereby cause damage to the bit body in the form of chipping, cracking, and other types of wear. In an embodiment, the drilling fluid 214 contains regenerative nanoparticles and the drill bit 200 includes magnetic particles. As described in more detail below, the magnetic particles attract the regenerative nanoparticles to the surface of the drill bit to regenerate damaged surfaces of the drill bit 200 and mitigate the effects of chipping, galling, cracking, and other wear.

FIG. 3 illustrates a cross-section of one embodiment of a roller cone of the roller cone drill bit of FIG. 1, as indicated by the section line A-A′ of FIG. 1. The roller cone drill bit 300 includes a roller cone 304 and a support arm 308. The roller cone 304 is supported on bearings 334 and a spindle 336. The roller cone 304, which may also be referred to as a bit body or a roller cone bit body, includes magnetic material 345 and surrounding regenerative material 350 that includes nanoparticles. In an embodiment, the roller cone 304 may be composed of a primarily tungsten carbide particulate phase, a binder (cobalt), and magnetic particles 345, which may be included with the particulate phase. In another embodiment, the roller cone 304 may be composed of casted steel and embedded magnetic particles 345.

According to an illustrative embodiment, in operation, the drilling fluid surrounding the roller cone bit includes regenerative materials 350. The particles of regenerative material 350 may be nanoparticles. More particularly, in many, the regenerative materials 350 may be superparamagnetic iron oxide nanoparticles. For illustrative purposes, the roller cone 304 includes a chip 360 and a crack 365, which serve as examples of damage to the roller cone 304 that may occur during drilling operations. The chip 360 and crack 365 expose areas of the roller cone 304 that include rough, damaged surfaces that may be subject to additional frictional wear, or galling, as cuttings from the wellbore are circulated over the surface of the roller cone 304. To regenerate damaged areas and protect the surface of the roller cone 304 during drilling operations, regenerative materials 350 suspended in drilling fluid may be constantly drawn to the magnetic materials 345 of the roller cone 304 to fill voids and form a protective film over the surface of the roller cone 304.

The regenerative materials 350 may not, however, permanently stick to the outer surface of the roller cone 304. In an embodiment, the regenerative materials 350 are scraped away from the surface of the roller cone 304 by shear forces of fluid and cuttings that flow over the surface of the roller cone 304 during drilling. Nonetheless, in an embodiment, constant magnetic attraction of the regenerative materials 350 to magnetic materials 345 may increase the longevity of the roller cone 304 by forming a transient, protective film of attracted regenerative material 350 at the surface of the bit body. Longevity of the bit body may also be increased by filling cracks and other voids in the bit body with regenerative materials 350. In the case of chip 360 or crack 365, for example, regenerative material 350 fills the chip 360 and crack 345, and bonding may occur at roughened, damaged surfaces resulting from, for example, the non-smooth crack 365 or chip 360. The magnetic bonding of the magnetic materials 340 to the regenerative materials 350 causes nanoparticles in the regenerative materials 350 to fill the chip 360 and crack 365, enabling the surface of the bit body to better resist frictional forces and wearing away for a longer period of time. Filling of cracks 365 and chips 360 with regenerative materials 350 may also insulate the roller cone 304 from further damage by forming a protective nanofilm of the nanoparticles at the surface of the drill bit 300 that prevents damaging particles from entering the damaged areas.

FIG. 4 illustrates a cross-section of the roller cone 304 of FIG. 3, showing the migration of regenerative materials 350 from a circulating drilling fluid into the chip 360 and crack 365. Here, the magnetic particles 345 attract regenerative materials 350, and regenerative materials 350A fill into chip 360 and crack 365 to regenerate and repair the drill bit. This process may occur repeatedly during the drilling process to form a regenerative drill bit. Recalling that the regenerative materials 350 may be magnetized nanoparticles, it is noted that chip 360 and crack 365 are not illustrated to scale, and in operation will likely be much smaller, having dimensions that are more appropriately measured on the microscale (in micrometers) or nanoscale (in nanometers).

In an embodiment, the roller cone 304 is formed according to known sintering techniques. A particulate phase including a powder such as tungsten carbide and rare earth magnets that form the magnetic material 340 may be mixed with binder material to form the body of the drill bit 300. This mixture is placed in a mold for sintering and heated to form the drill bit body. Possible rare earth magnets that may be used in the drill bit body 304 include, but are not limited to, AlNiCo, NdFeB, and SmCo. As referenced herein, “AlNiCo” refers to iron alloys having a composition of 8-12% aluminum, 15-26% nickel, 5-24% Cobalt, up to 6% copper, up to 1% titanium, and iron; “NdFeB” refers to a neodymium magnet having a composition Nd2Fe14B in a tetragonal crystalline structure; and “SmCo” refers to samarium-cobalt magnets having a typical composition of SmCo5. It is important to consider the temperature ranges these rare earth magnets can sustain since the drill bit is heated during the sintering process and during the drilling process. The working temperature ranges for the aforementioned materials are: from 350° C. to 550° C. for AlNiCo; below 200° C. for NdFeB; and from 250° C. to 350° C. for SmCo. The maximum temperature that the bit needs to reach during fabrication and the maximum likely temperature of the bit during drilling, therefore, may be considered in selecting the appropriate rare earth magnet to use in a particular drill bit body. In a formation that is expected to be at 350° C., for example, AlNiCo may be the appropriate rare earth magnet for use in the bit body.

Referring now to FIG. 5 a cross-sectional diagram of a portion of a fixed cutter drill bit 500 is shown. The drill bit body 504 of the drill bit 500 is a matrix drill bit body that includes magnetic particles 545. The fixed cutter drill bit 500 may be composed of, for example, a particulate phase of tungsten carbide and magnetic particles 545, and a binder material, like the roller cone drill bit body described previously.

In an embodiment, drilling fluid surrounding the fixed cutter drill bit 500 includes regenerative materials 550 including nanoparticles and, alternatively, other regenerative materials. The regenerative materials 550 may be superparamagnetic iron oxide nanoparticles. As shown, regenerative nanoparticles 550 are responsive to and attracted to magnetic particles 545 embedded in the fixed cutter drill bit body 504. During drilling operations, chip 560 or crack 565 may occur in the fixed cutter drill bit body 504. The chip 560 or crack 565 exposes an area that includes a rough surface at the location of the crack 565 or chip 560. During drilling operations, regenerative materials 550 may be constantly drawn to the surface of the fixed cutter drill bit 500 by drilling fluid circulated in the drill string and wellbore. The regenerative materials 550, however, may not stick to the fixed cutter drill bit body 504 permanently due to the frictional forces created by circulation of the drilling fluid and movement of the bit relative to the wellbore and cuttings in the drilling fluid. Nonetheless, constant magnetic attraction of the regenerative materials 550 to the magnetic particles 545 may increase the longevity of the fixed cutter drill bit 500 by forming a protective nanofilm that insulates the surface of the drill bit body as described above with regard to the roller cone 304 of FIG. 3. In the case of a chip 560 or crack 565 that is filled by regenerative materials 550, it is noted that increased bonding may occur due to the roughened surface of the bit body 504 resulting from the non-smooth crack 545 or chip 560 in the material. Regenerative materials 550 that are magnetically attracted to areas such as chip 560 or crack 565 may thereby provide a more complete filling of chip 560 or crack 565. Also, the filling of such areas with regenerative materials 550 and formation of a protective nanofilm will further insulate and protect the surface of the fixed cutter bit 500 by preventing damaging particles from entering the areas of the crack 565 and chip 560.

FIG. 6 illustrates a cross-section of the fixed cutter drill bit 500 of FIG. 5 and shows the migration of regenerative materials 550 into the chip 560 and crack 565 in the manner described above with regard to FIGS. 3 and 4. The magnetic particles 545 attract the regenerative materials 550 so that regenerative nanoparticles 550A are attracted into the chip 560 and crack 565 to form a repaired drill bit 500. This process may occur continuously and repeatedly during drilling.

As described above in relation to the roller cone bit body 304 of FIGS. 3 and 4, the fixed cutter bit body 500 may be formed according to known sintering, casting, and other suitable fabrication techniques. For example, a particulate phase including a powder such as tungsten carbide and rare earth magnets that form the magnetic material 540 may be mixed with binder material to form the body of the drill bit 500. This mixture may be placed in a mold for sintering and heated to form the drill bit body.

In an embodiment, magnetic particles of the types described previously are formed or magnetized in situ in a drill bit body by heating a magnetizable material above its Curie temperature, putting the heated material in an electromagnetic field, and then cooling. This may be performed during the infiltration of binder material into a particulate phase that includes a hard material powder and magnetizable material during, for example, a sintering fabrication process. In an embodiment, the sintering fabrication process is used to heat the magnetizable material to or above its Curie temperature. Magnetization may be achieved by applying a magnetic field to the magnetizable material at the Curie temperature as the bit body is being cooled. In an embodiment, the material is magnetized during the cooling process instead of at a prior time during the fabrication process to minimize the effects of material migration that may occur if the binder has increased permeability at higher temperatures. To magnetize the magnetic particles, an electromagnetic field is applied to the drill bit when the material is at the Curie temperature for the material to be magnetized. Examples of some relevant Curie temperatures for suitable magnetic materials are: FE 770° C. for iron; Co 1130° C. for cobalt; Ni 358° C. for nickel; and 622° C. for iron oxide.

In another embodiment, magnetizable materials such as superparamagnetic nanoparticles in the drilling fluid may be used to identify leak-off zones in a wellbore using magnetic resonance imaging (MRI) or nuclear magnetic resonance imaging (NMR) in a logging while drilling (LWD) process. Since the superparamagnetic nanoparticles will be circulated throughout the drill string and wellbore in the drilling fluid, and because such nanoparticles carry a very strong magnetic charge with a single pole, the nanoparticles are easily detectable by such imaging systems. In some embodiments, leaching drilling fluid may be detected via MRI/NMR systems that detect the superparamagnetic nanoparticles in the drilling fluid.

In some embodiments, if a non-matrix drill bit is used, then small amounts of magnetic material may still be included in portions of the drill bit. In the case of drill bits made of steel, for example, the composition of the steel may be adjusted to include iron that may be magnetically charged by applying a magnetic field during formation at Curie temperatures as described above. Rare earth magnets might also be used, but their magnetic properties may be destroyed during the high temperatures used to form steel. In such embodiments, permanent magnets or other suitable magnets may be used to attract the regenerative materials.

In another embodiment, as shown in the schematic drawing of FIG. 7, a drill bit 604 may include or be coupled to an electromagnet 606 that is deployed adjacent the drill bit 604 in a drill string 608. The electromagnet 606 may be an assembly that is integral to the assembly of the drill bit 604, or included within a collar or other member of the drill sting 602 that is proximate to the drill bit 604. In either case, the electromagnet is magnetically coupled to the drill bit and operable to induce a magnetic polarity in magnetic materials included in the drill bit 604, thereby causing the magnetic materials of the drill bit to transmit a magnetic field. In an embodiment in which the drill string 604 is also operable to detect leaching of drilling fluid by monitoring the movement of superparamagnetic particles or other magnetic particles in a drilling fluid, the drill string 602 also includes a LWD module 610, which may be a MRI or NMR module that may track or detect the presence of magnetic or superparamagnetic particles at locations in the wellbore in which the module 610 is deployed.

FIG. 8 is a block diagram showing elements of a portion of the system described with regard to FIG. 7. As shown in FIG. 8, in an illustrative embodiment, the electromagnet 706 includes an electromagnet, which may be, for example, a conductive coil 714. The electromagnet is magnetically coupled to the drill bit 704 to apply a magnetic field that extends to (and beyond) the exterior of the body of the drill bit, with sufficient magnitude to interact with the regenerative nanoparticles in the drilling fluid flowing over the surface of the drill bit. The amount of current and voltage supplied to the conductive coil 714 is controlled by a controller 704, which is in turn coupled to a power source 710. The controller 704 may also be coupled to a transceiver 712, which may be any suitable wired or wireless transceiver that communicatively couples the controller 708 with a surface based controller for the purposes of receiving an actuation signal that results in the activation and deactivation of the electromagnet 714, and optionally to control the magnitude of the magnetic field generated by the electromagnet. The electromagnet 714 thus enables selective magnetization of the drill bit body. The magnetic field may be generated with sufficient magnitude to attract regenerative nanoparticles and cause the regenerative nanoparticles to attach to the surface of the drill bit body when the electromagnet is operational. The selective magnetization may include selectively reducing or deactivating the magnetic field, enabling the drill bit to release the regenerative nanoparticles that had previously been attached to the surface of the drill bit body so that the drill bit and surrounding area may be flushed out when desired.

Applying the foregoing concepts, systems, and methods, it is again noted that the duration of time a drill bit, such as a fixed cutter drill bit, roller cone drill bit, or other type of drill bit, will last without becoming heavily damaged is an important factor in being able to continuously perform drilling operations. By providing a drill bit that may regenerate or form a protective film in the presence of regenerative materials (such as regenerative nanoparticles circulated in drilling fluid), the window for continuously performing drilling operations may be expanded. This disclosure therefore describes systems, tools, and methods for providing a regenerating drill bit that is capable of attracting regenerative nanoparticles to repair and insulate the surface of the drill bit body using magnetic materials embedded in the drill bit body. In addition to the embodiments described above, many examples of specific combinations are within the scope of the disclosure, some of which are detailed in the following examples:

Example 1

A wellbore formation system comprising:

-   -   a drill bit having at least one cutting element and a drill bit         body comprising a magnetized material that generates a magnetic         field extending to an exterior of the drill bit body;     -   a drilling fluid comprising magnetizable regenerative particles;         and     -   a fluid flow path that guides the drilling fluid through a drill         string and over a surface of the drill bit.

Example 2

The system of example 1 wherein, the regenerative particles comprise superparamagnetic nanoparticles.

Example 3

The system of example 2, wherein the superparamagnetic nanoparticles comprise iron oxide.

Example 4

The system of example 1, wherein the drill bit body is a matrix drill bit body, and wherein the matrix drill bit body comprises:

-   -   a particulate phase and a binder material, the particulate phase         comprising magnetic particles.

Example 5

The system of example 1, further comprising an electromagnet, wherein the drill bit body is a matrix drill bit body, and wherein the matrix drill bit body comprises:

-   -   a particulate phase and a binder material, the particulate phase         comprising ferromagnetic particles; and     -   wherein the drill bit is magnetically coupled to the         electromagnet.

Example 6

The system of example 1, further comprising an electromagnet, wherein the drill bit body is a matrix drill bit body, and wherein the matrix drill bit body comprises:

-   -   a particulate phase and a binder material, the particulate phase         comprising particles of rare earth magnet.

Example 7

The system of example 6, wherein the rare earth magnet is selected from the group consisting of AlNiCo, a neodymium magnet, and a samarium-cobalt magnet.

Example 8

The system of example 1 wherein the drilling fluid is a water-based drilling fluid, and wherein the regenerative materials are functionalized for dissolution in water.

Example 9

The system of example 1 wherein the drilling fluid is an oil-based drilling fluid, and wherein the regenerative materials are functionalized for dissolution in oil.

Example 10

A method of preserving a drill bit surface, the method comprising:

-   -   providing a drill bit having a magnetized drill bit body that         generates a magnetic field extending to an exterior of the drill         bit body;     -   operating the drill bit to form a wellbore, the drill bit         comprising the drill bit body; and     -   circulating a fluid over a surface of the drill bit body to         regenerate a surface of the drill bit body, the fluid comprising         regenerative materials that are magnetically attracted to the         magnetized drill bit body.

Example 11

The method of example 10, wherein the regenerative materials comprise iron oxide nanoparticles.

Example 12

The method of example 10, wherein the regenerative materials comprise superparamagnetic particles.

Example 13

The method of example 10, wherein the drill bit comprises a matrix drill bit body having a particulate phase component, a binder material, the particulate phase including tungsten carbide, and the magnetic particles.

Example 14

The method of example 13, further comprising activating an electromagnet, wherein the magnetic particles comprise a ferromagnetic material that becomes magnetized in response to activation of the electromagnet.

Example 15

The method of example 10, wherein the magnetic particles comprise particles of rare earth magnet selected from the group consisting of AlNiCo, neodymium magnet, and samarium-cobalt magnet.

Example 16

The method of example 10, further comprising forming a protective film of the regenerative materials at a surface of the drill bit body by magnetically attracting the regenerative materials to the surface of the drill bit body.

Example 17

A method of manufacturing a drill bit body comprising:

-   -   placing a particulate phase and a binder material into a mold,         the particulate phase including tungsten carbide and         magnetizable particles; and     -   sintering the particulate phase and the binder to form a drill         bit body.

Example 18

The method of example 17, further comprising cooling the drill bit body following the step of sintering the particulate phase and the binder to form the drill bit body; and, while cooling the drill bit body, applying a magnetic field to the drill bit body.

Example 19

The method of example 18, wherein applying the magnetic field to the drill bit body comprises applying a magnetic field to the drill bit body when the magnetizable particles are at the Curie temperature.

Example 20

The method of example 17, wherein the magnetizable particles comprise particles of rare earth magnet selected from the group consisting of AlNiCo magnet, a neodymium, and samarium-cobalt.

It should be apparent from the foregoing that embodiments having significant advantages have been provided. While the embodiments are shown in only a few forms, the embodiments are not limited, but are susceptible to various changes and modifications without departing from the spirit thereof. 

We claim:
 1. A wellbore formation system comprising: a drill bit having at least one cutting element and a drill bit body comprising a magnetized material that generates a magnetic field extending to an exterior of the drill bit body; a drilling fluid comprising magnetizable regenerative particles; and a fluid flow path that guides the drilling fluid through a drill string and over a surface of the drill bit.
 2. The system of claim 1 wherein, the regenerative particles comprise superparamagnetic nanoparticles.
 3. The system of claim 2, wherein the superparamagnetic nanoparticles comprise iron oxide.
 4. The system of claim 1, wherein the drill bit body is a matrix drill bit body, and wherein the matrix drill bit body comprises: a particulate phase and a binder material, the particulate phase comprising magnetic particles.
 5. The system of claim 1, further comprising: an electromagnet, wherein the drill bit body is a matrix drill bit body comprising a particulate phase and a binder material, the particulate phase comprising ferromagnetic particles; and wherein the drill bit body is magnetically coupled to the electromagnet.
 6. The system of claim 1, wherein the drill bit body is a matrix drill bit body, and wherein the matrix drill bit body comprises: a particulate phase and a binder material, the particulate phase comprising particles of rare earth magnet.
 7. The system of claim 6, wherein the rare earth magnet is selected from the group consisting of AlNiCo, a neodymium magnet, and a samarium-cobalt magnet.
 8. The system of claim 1 wherein the drilling fluid is a water-based drilling fluid, and wherein the regenerative materials are functionalized for dissolution in water.
 9. The system of claim 1 wherein the drilling fluid is an oil-based drilling fluid, and wherein the regenerative materials are functionalized for dissolution in oil.
 10. A method of preserving a drill bit surface, the method comprising: providing a drill bit having a magnetized drill bit body that generates a magnetic field extending to an exterior of the drill bit body; operating the drill bit to form a wellbore; and circulating a fluid over a surface of the drill bit body to regenerate a surface of the drill bit body, the fluid comprising regenerative materials that are magnetically attracted to the magnetized drill bit body.
 11. The method of claim 10, wherein the regenerative materials comprise iron oxide nanoparticles.
 12. The method of claim 10, wherein the regenerative materials comprise superparamagnetic particles.
 13. The method of claim 10, wherein the drill bit comprises a matrix drill bit body having a particulate phase component, a binder material, the particulate phase including tungsten carbide, and the magnetic particles.
 14. The method of claim 13, further comprising activating an electromagnet, wherein the magnetic particles comprise a ferromagnetic material that becomes magnetized in response to activation of the electromagnet.
 15. The method of claim 10, wherein the magnetic particles comprise particles of rare earth magnet selected from the group consisting of AlNiCo, neodymium magnet, and samarium-cobalt magnet.
 16. The method of claim 10, further comprising forming a protective film of the regenerative materials at a surface of the drill bit body by magnetically attracting the regenerative materials to the surface of the drill bit body.
 17. A method of manufacturing a drill bit body comprising: placing a particulate phase and a binder material into a mold, the particulate phase including tungsten carbide and magnetizable particles; and sintering the particulate phase and the binder to form a drill bit body.
 18. The method of claim 17, further comprising cooling the drill bit body following the step of sintering the particulate phase and the binder to form the drill bit body; and, while cooling the drill bit body, applying a magnetic field to the drill bit body.
 19. The method of claim 18, wherein applying the magnetic field to the drill bit body comprises applying a magnetic field to the drill bit body when the magnetizable particles are at the Curie temperature.
 20. The method of claim 17, wherein the magnetizable particles comprise particles of rare earth magnet selected from the group consisting of AlNiCo magnet, a neodymium, and samarium-cobalt. 